WARNING!!! THIS COULD PERMENANTLY BRICK YOUR PHONE!!! Please fully understand that this may cause some unwanted problem. Make sure you can take the risk. YOU'VE BEEN WARNED.
(This method may only works on Kernel Version: 18.104.22.168-gd2764ed. This information can be found in Settings->About phone->Software information)
and then click 'Temproot now', and wait.